Give the interpreter real Celtic Cross meanings and --format/--lang support

- guidance.c now prints last, after the full spread; both it and main.c's
  new Celtic Cross readout pull real Waite card meanings via tarot_data.c
  instead of just naming cards.
- interpreter-cli gains --format text|html|json and --lang en|de, matching
  deck-engine - required linking engine/src/tarot_data.c and i18n.c into
  the interpreter binary (a narrow, documented exception to its earlier
  "no engine .c files" policy) and writing German translations for
  narrative.c's/guidance.c's own text.

interpreter/src/narrative.h

@@ -39,7 +39,13 @@
  * personalized way transits are read (see astro.h's own house-field
  * comment). Pass a value outside 1-12 (e.g. the "no data" sentinel `0`
  * used elsewhere - see reading_io.c's parse_bodies()) to omit that
- * framing and print the planet's narrative on its own. */
+ * framing and print the planet's narrative on its own.
+ *
+ * Every string here is looked up via i18n_get() under "narrative.*"
+ * keys (engine/i18n's .lang files) before falling back to the English text
+ * baked into narrative.c, the same catalog tarot_data.c uses - so this
+ * text respects whatever --lang the caller loaded with i18n_load()
+ * (main.c does so before calling this). */
 void narrative_print(FILE *out, const char *indent, const Aspect *aspect,
                       int transiting_house);